The instant invention relates to a fiber feed tube for use in a concrete batch mixing truck that provides the ability to provide preloaded containers, having measured quantities of reinforcing fibers or other concrete admixtures for use in the admixture feed section of a concrete batch mixer. More specifically, this invention relates to a tube shaped container having sealed ends for the purpose of containing concrete admixtures and serving as a distribution reservoir in a concrete batch mixing system.
Construction concrete, particularly that used for roads and structures, has long been the mainstay of the American infrastructure. However, the uses to which concrete can be put is limited by the strength of the concrete material. Generally, while concrete has a great deal of strength in compression, it tends to have poor structural properties when subjected to tensile forces. For example, when used as a column where all of the weight is transferred in a linear fashion, the properties of the concrete alone are often sufficient to transfer the weight. However, when used as a beam, strengthening members must be added to assist in transferring the load. It has been a goal in the industry for many years to strengthen the concrete""s structural properties by using certain additives and varying the relative quantity of materials in the concrete mixture. One approach to enhancing the tensile strength of the concrete mixture consists of adding fibers, such as those made of fiberglass, nylon, polypropylene, or other fibrous materials to the concrete mixture. The addition of these fibers increases the tensile strength of the concrete mixture in its cured state. It is therefore common to dose a quantity of concrete with a quantity of these fibers during the mixing stage before the concrete is placed. One of the problems with adding these fibers in raw form at the mixing stage is that they tend to clump together resulting in an uneven distribution throughout the concrete mixture.
Generally, concrete is made in two ways. The first method is known as the batch method. Simply put, it occurs when an individual creates only one batch of concrete at a time by adding a specified and predetermined amount of ingredients in a mixing caldron or cement mixing truck. Concrete produced using this method is particularly unsuited for the addition of fibers as it is particularly susceptible to the clumping issue identified above. A second method that is more economical is known as the continuous production method. In the continuous production method, concrete is continually produced using a series of conveyor belts and mixing machines and once the mix is completed, it is transported to its final destination. This transportation could be either along further conveyors or through pumps if the material is mixed relatively close to the location at which it will be used or through trucks if the mixing location is remote from the ultimate use location.
A method used in the prior art for incorporating admixtures into batch mixed concrete includes the use of a xe2x80x9cpillxe2x80x9d. This method consists of dropping a small paper bag containing a measured amount of admixture material into a known quantity of concrete mixture, as the concrete is mixed, the bag breaks, releasing the admixture into the concrete. Using this method however has drawbacks, as the bag does not always break completely, trapping a portion of the admixture and preventing it from being incorporated into the concrete mixture.
Another system incorporating the use of an admixture feeder was developed to provide a means for introducing fibrous material or other admixtures into a continuous flow of concrete that is produced using the continuous production method described above. The admixture feeder is comprised of a hopper that holds the admixture material. An aperture is located at the bottom of the hopper through which admixture material is forced. A ram or piston pushes the material through the hopper and out the aperture. As the admixture material emerges from the aperture, rotating fingers agitate it and cause it to fall out of the opening. The material then falls onto a conveyor and is mixed with the other concrete ingredients. The difficulty with this particular system is that the hopper system is a fixed component of the device. Therefore, in order to operate, periodically the ram must be withdrawn from the hopper and the hopper refilled. This is particularly troublesome due to the fact that most concrete admixtures are packaged and sold in large bags or drums that are difficult to handle. In transferring the admixture material from the original packaging into the hopper, there is a risk of contamination and spillage. The operator must scoop or pour the raw material into the hopper that is a fixed component on the mixing machine. Further, there is no real control available to carefully measure the amount of material that is added to the hopper.
While concrete may be thought of as a rough simple mixture, the science of concrete admixtures actually requires pure materials and carefully measured admixtures. Both the risk of contamination of the admixture and the inability to effectively measure the quantity of admixture material that is added to the hopper can greatly affect the final strength of the cured concrete material. It can therefore be seen that the current state of the art is a less than desirable solution for incorporating admixtures into the concrete mixing process. There is, therefore, a need for the development of an apparatus that will overcome the above noted drawbacks by reducing the amount of handling required in transferring the concrete admixture material to the feeding system. Further, there is a need to provide an apparatus that can provide a controlled and measured dose of admixture for even distribution and incorporation into a concrete mixture. Another object of this invention is to provide an apparatus for packaging concrete admixtures in a manner that allows them to be distributed, sold and incorporated into a concrete system without requiring additional handling by the operator thereby reducing the possibility of contamination or inaccurate measurement.
In this regard, the present invention provides a solution for efficient and clean handling of concrete admixtures in a pre-measured and controlled manner. The present invention provides a novel packaging system to be integrated into the admixture feed devices on a concrete batch mixing truck allowing transfer and incorporation of the admixture material to the concrete without additional handling by the operator. This system thereby eliminates the possibility of spillage of the admixture material by eliminating the need to scoop or otherwise transfer the material from a bulk package into the feed hopper on the mixing machine. In addition, the admixture material can be carefully pre-measured at the packaging/distribution point in a clean controlled environment rather than in the field where careful measurement is difficult and the risk of contamination is high.
The present invention consists of a tubular package of heavy gauge cardboard or plastic material such as PVC with an easily removable, yet securely affixed, light gauge cover on each end. The cover would be constructed of a material that could be easily displaced when installing the tube into the feeder section of the mixer and for example could be a heavy coated paper. The tube is pre-loaded with any variety of clean pre-measured concrete admixtures. As can be seen the present invention eliminates the need of handling the admixture materials prior to their incorporation into the concrete and provides a cleaner, more precise distribution system.
Other objects, features and advantages of the invention shall become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings.